As you can see, there are a few "top tier" manufacturers, and then the rest.

COLT MSRP: $1250*

Altogether, Colt puts out the rifle to beat. There is one minor issue you might want to know about before you buy your Colt.

Non-milspec FCG pins

Colt uses non-standard size Fire Control Group pins. This makes it impossible to switch trigger groups from a Colt to an LMT/RRA/CMMG/or anyone else. Colt is the ONLY manufacturer doing this. Most aftermarket triggers make both standard pins, and non-standard pins, so this isnt much of an issue, but it would stink to go out and buy an aftermarket trigger only to find out it wont fit.

Other than the political differences I have with Colt, I would gladly choose a Colt LE6920 to go into harm's way. The issue listed above should be ranked somewhere between minor and frivolous compared to the excellent product you would be getting by buying a Colt.
Here's some more pics:

*Price taken from my personal knowledge. One other problem with Colts, is that they bow at the altar of the Military, and only release LE guns every now and then when they have overruns. This makes the price fluctuate wildly. At times, LE6920s can be found for $1150, but don't count on it! Other times they can only be found for $1400 and UP!

LMT MSRP: $1123*

Shockingly, LMT does not use taper pins on the FSB, they do not parkerize under the FSB, nor do they come with double heat shielded guards nor the "H" buffer.

As far as the buffer goes, who cares if it runs. I've never heard of people complaining that their LMT rifles don't run well without a buffer swap, so this doesn't bother me in the slightest.

The heat shielded handguards is (again) really just for full-auto, but LMT is of such high quality (and price) that I figured they would include them. Oh well...

However, it is the lack of taper pins that actually surprises me the most. I am shocked that LMT does not use the most proven method of fixing the FSB to the barrel. Instead, LMT uses STRAIGHT pins to attach the FSB. While this method has not caused any FSBs to come loose on LMT rifles (that I know of), it still leaves a blank on the chart. I don't think this should cause any great concern.

The parkerizing (as mentioned above) is really just a trivial matter that most will never realize. It's just one of those "attention to detail" matters.

The Noveske N4 hits on all cylinders! The one blank on the chart is the black insert. While this looks surprising, the black insert is not the only way to get a carbine to extract. O-rings, Defender Rings, and double springs also work. Noveske's bolt uses a Viton-2 O-Ring over the extractor spring. This should be considered a "check" for that blank, but the chart is limited.

The price is the highest of the group, but it comes standard with the most accessories. The Tango Down Battlegrip is $30 compared to a $5 A2 grip, the Vortex FH is $50 compared to a $5 A2 birdcage, the rear sight (no brand named) is easily worth $50, and the VLTOR modstock goes for about $50 more than a standard M4 stock. That's $180 worth of accessories you are getting included (whether you wanted them or not!?)

On the chart, CMMG is to the right of both S&W and Sabre Defense, but I don't know why. I personally consider the manufacturer that provides the bells and whistles as an upgrade option to be "higher" than those which do not.

CMMG's base rifle comes complete with a standard bolt, which is fine for 99% of users. In fact, this is the bolt that is in my rifle. However, if you want the "bells and whistles", and you don't mind parting with another $30, then you can upgrade to the EGRESS bolt, which has the following:

This checks off most of the blanks on the chart except for the "properly staked gas key." Well, it's true, CMMG FORMERLY did not use the "proper" technique set out in Colt's TDP, but let's take a look. Here is MY bolt carrier which was bought circa 2005:

Notice the screws (circled in red) have been "set" by the slash cuts. That is not the "correct" way to do it, but it had worked for me. I would like for it to be "properly" staked, but like LMT's use of straight pins, CMMG does not suffer from any negative reputation for gas keys coming loose.

CMMG currently ships all carriers with properly staked gas keys. Warpig8654 has provided this picture of a recently purchased CMMG carrier which is properly staked:

In addition, I checked with Jeff at CMMG to be sure this was now standard. He informed me that not only is this standard, but he also advised that all of their bolts are shot peened and MP tested. Their barrels are certified rifle grade mil spec 4150 steel and are MP tested. They are also going to implement staking the castle nut, but haven't started yet. In addition, they now use a 5 position mil spec receiver extensions on all builds, just like Colt does.

As for the buffer, just like Noveske, if it works it works. CMMG offers the "Standard" buffer at no charge, and only adds $10 if you want the "H" buffer, or "H2" buffer. (If you want the Tungsten buffer it's a bit more.)

One really neat thing about the CMMG, is that the M16 bolt carrier is a free option. Just click it in the drop-down menu and it's yours. I like this carrier, because it's slightly heavier, delaying the unlocking just a tad bit. It's the correct carrier, which Colt now includes in the LE6920. It does NOT make your rifle somehow "illegal" for having an M16 part in the rifle. That is a myth.

Here's the CMMG M16 carrier:
Check out the M4 feedramps on the CMMG. Beautiful!
And of course the firing pin is fully shrouded:
In Summary: it's a BUY!

*Price taken from their website by adding the price of a complete lower and upper in M4 configuration

S&W M&P15 MSRP: $989*

This rifle is a fine rifle in most aspects, and will serve its user well. Let me speak to just a few issues:

The barrel is not offered in 1/7 twist, and it does not come with M4 feedramps*. While the manufacturer claims it comes with a F-marked FSB, reports indicate this is not true. No parkerizing under the FSB, no double heat-shielded handguards, but most importantly, no lifetime warranty.

* Reports from new owners indicate that S&W is now (10/21/08) offering extended feedramps on their rifles. I am not sure when this move took place, or which rifles will come with this feature.

While nearly all of the above issues are forgivable, the lack of a warranty makes this option extremely distasteful. I'd like to think S&W will stand behind the products they market (not sure they actually MAKE this rifle), but they do not have a written warranty and I have no knowledge of personal experience with returns.

While Sabre does not have some of the "Voodoo" specified by the TDP, it is nonetheless a fine rifle. It lacks only the double heat shields and the "H" buffer.

However, Sabre, like S&W, does not have a written lifetime warranty. This causes me concern. Although it appears to be a fine rifle built with the correct parts, it doesn't have that security blanket of a company that stands behind it's product.

It is well written, but for the most part, puts too much emphasis on things that most people won't need. Most people will never need a third of the things on those rifles...

Sorry guys did not mean to offend anyone or raid material which is why I put the link at the top. I just wanted to make this available to those who are trying to learn about AR 15's and felt this would be an article that would help build a base of general knowledge.

For those like myself that are trying to get as much info as possible the other post on how to build an ar is very good. The link to www.brownwells.com where they go through in detail with video on how to build an ar is excellent.

It is well written, but for the most part, puts too much emphasis on things that most people won't need. Most people will never need a third of the things on those rifles...

I would agree with you, but keep in mind that the author was former Leo, intending on providing information for other like minded Leo's. Whether or not they need all that stuff is also debatable - but the article wasn't written for us here, so we can't question the author...

Again, we run into those "in the know" preaching to the masses about what "is needed" on a rifle of this type. There isn't anything new there from the standpoint of opinion/preference versus actually needed in the real world.